Qitzur Shulchan Arukh – 181:9
A person may obtain justice for themselves. If he wants his item, which is in the possession of someone else who stole it, he can take it from his possession. And if the other stands in his way, he can beat him until he puts the item down. [But this is only] if he can not save it another way, even if it’s an item that is not perishable, if he were to wait until he can stand him in court.
If there are witnesses who see him taking the item from the possession of the other, he can not grab it via hitting unless he can prove afterward that he took his own [property]. Because if he can’t prove it, the grabbing [of his item] won’t help him, since there are witnesses for the matter [who could be brought to court to force him to return it]. But if there are no witnesses, he may do so, even where he does not have the ability to prove [that the item is really his].